Description: Research suggests that: (1) orbital debris has reached an unstable point whereby, even with no future launches, the amount of debris will continue to grow through collisions among large-body debris, and (2) removing as few as five large objects each year can stabilize debris growth. For large-body active debris removal (ADR), active technologies are required to safely and efficiently stabilize and capture the target debris. The interactions of these complex electromechanical systems (eg. imaging systems, LIDAR, robotic arms and grippers, etc) and control algorithms pose challenges best addressed by hardware-in-the-loop testing. Given the risks inherent in non-cooperative spacecraft proximity operations, and the firm requirement that ADR missions do not themselves produce additional debris, realistic ground-based testing is required for risk reduction. Testing space operations in ground-based facilities is notoriously difficult and limited. Our proposed approach significantly increases the capability and fidelity of such testing operations and elevates the chance of a successful ADR mission. We propose a combination of robotic technologies to allow for a large range of relative motion simulation with accurate contact dynamics. First, the target debris object is suspended from a thin rod and spun up to a desired rotational speed. The suspension point is actively controlled to remove the periodic pendulum effect while still allowing free motion from contact, and a universal joint permits free rotational motion. Second, the chaser spacecraft is mounted atop HOMER, an omnidirectional robot capable of unlimited planar motion and limited-range out-of-plane motion. HOMER was designed and built by Texas A&M to emulate the 6-DOF relative-motion trajectories common in spacecraft proximity operations. Along with careful attention paid to the design of mock-targets, these two systems will allow for large-scale motion with accurate contact dynamics for high-fidelity ADR testing.

Benefits: Realistic ground-based testing of spacecraft proximity operations provides significant risk reduction for any active debris removal mission. The LASR Lab is uniquely capable of providing full 6-DOF relative motion capabilities at low cost. The testing and validation of the high-accuracy 6-DOF feedback tracking on HOMER, combined with the pendulum-based equivalent of a 5-DOF air bearing, will certify LASR Lab as a world-class test facility - a true dynamics version of a wind tunnel. VectorNav plans to serve as a commercial partner to LASR Lab, providing design of experiments support whenever customers contract with the LASR Lab for testing. The details gleaned from the Mock Target Trade Study places VectorNav in a prime position to design realistic experiments for a wide variety of customers at LASR Lab and other simulation facilities.

The advanced capabilities of the LASR Lab to provide high-fidelity, hardware-in-the-loop testing is broadly applicable to any spacecraft proximity operations mission, as is the know-how generated by the Mock Target Trade Study by VectorNav. VectorNav and the LASR Lab will be able to provide extensive support and testing facilities for a wide range of customers, both commercial and governmental. Missions supported include among others: GEO refueling, on-orbit servicing, and fractionated spacecraft.